This project attempts to investigate the nature of interactions between components of the pre-corneal tear film and corneal epithelial surface, to elucidate the phenomena of epithelial non-wettability and functions of the Meibomian lipid and conjunctival mucin. A complete analysis of the lipid by quantitative chromatographic techniques will be performed; viscous and spreading properties of the lipid, and its surface interaction with mucin, will be investigated. The influence of degree of roughness of the epithelial surface on retention of mucin, and the thickness of mucin layers, as well as the influence of epithelial charge or pre-adsorbed lipids on mucin binding, will be determined by electron microscopy and electron autoradiograpy of thin sections of cornea and artificial surfaces. Surface parameters (dynamic contact angle and spreading) will be investigated for aqueous solutions on model surfaces of varying degrees of roughness and charge distribution, in the presence of mucins both native and modified by enzymic removal of prosthetic sugar groups; Meibomian lipids will also be studied by this method to determine their role (if any) in production of epithelial hydrophobicity. Surface membrane components will be isolated from cells in tissue culture for analysis to determine other possible sources of hydrophobic character. Charge distribution on intact epithelium and on model surfaces will be investigated by a streaming potential method.